CH 688 224 A5 discloses an implantable device for dispensing pharmaceutical fluids in the human or animal body in doses, wherein the implantable unit comprises: a cam-controlled, valve-less axial piston pump comprising a piston which can be rotary-driven and axially displaced; a fluid reservoir which is connected to the suction side of the pump; and a rotary drive which is connected to the piston and can be controlled, wherein a suction opening and a pressure opening are each arranged on a lower end of a cylinder, and the two openings lie diametrically opposite each other and run in the same axis.
U.S. Pat. No. 6,010,485 discloses a working cylinder having a similar design to that in CH 688 224 A5.
U.S. Pat. No. 6,749,587 B2 discloses a modular infusion apparatus comprising a measuring portion which can directly control the fluid flow between a reservoir and a cannula. If the reservoir is kept at ambient pressure, the measuring portion can comprise a peristaltic mechanism, a displacement pump or other pump device.
U.S. Pat. No. 4,643,723 discloses a device for administering insulin to a patient, wherein a piston is arranged in a pump chamber, a cannula is connected to the pump chamber, and a piston rod is connected to the piston. When the piston is retracted, the reservoir is connected to the pump chamber in order to fill up the pump chamber, and when the piston is moved forwards, the passage from the reservoir to the pump chamber is closed by means of a valve, such that the substance can be administered via a cannula.
WO 93/04714 and the corresponding EP 0 600 948 B1 disclose a fluid measuring element for an implantable administering system which is coupled between a pressurized fluid source and an outlet opening, in order to provide discrete flow pulses at a predetermined rate.
US 2004/0069044 A1 discloses a device for measuring a volume of a drug. The device comprises a first chamber which contains the fluid drug, a measuring chamber which is in fluid connection with the first chamber, and a measuring array.
U.S. Pat. No. 5,207,666 discloses a fluid measuring apparatus for implantable drug administering systems, which can be arranged between a pressurized fluid source and an outlet opening, in order to provide discrete flow pulses at a predetermined rate.
US 2005/0159708 A1 discloses an infusion pump for administering a fluid in doses, wherein a piston is permanently pressurized by means of a spring and acts on a drug container which dispenses the substance through a dispensing opening towards a control valve, in order to dose it.
EP 1 633 417 B1 discloses a dispensing apparatus comprising a storage chamber and an injection chamber which are coupled via a fluid connection and in each of which plungers are arranged.
There remains a need for a dosing device for an infusion system that enables a substance to be dosed precisely and dispensed simply.